College

Use synthetic division to find [tex]$P(k)$[/tex] given [tex]$k=5$[/tex] and [tex]$P(x)=x^2+x-30$[/tex].

Set up the synthetic division problem:

[tex]\[

\begin{array}{c|ccc}

5 & 1 & 1 & -30 \\

\end{array}

\][/tex]

Complete the synthetic division process to find the value of [tex]$P(5)$[/tex].

Answer :

Sure! To find [tex]\( P(k) \)[/tex] using synthetic division, let's set up and solve the problem using the given values and polynomial.

1. Identify the Polynomial and [tex]\( k \)[/tex]:
- Polynomial: [tex]\( P(x) = x^2 + x - 30 \)[/tex]
- [tex]\( k = 5 \)[/tex]

2. List the Coefficients:
The coefficients of [tex]\( P(x) \)[/tex] are:
- 1 (for [tex]\( x^2 \)[/tex])
- 1 (for [tex]\( x \)[/tex])
- -30 (constant term)

3. Set Up Synthetic Division:
Start the synthetic division by setting up the following:
- Write 5 (the value of [tex]\( k \)[/tex]) outside the division symbol.
- Write the coefficients of the polynomial in order inside the division symbol.

The setup looks like this:
```
5 | 1 1 -30
|
----------------
```

4. Perform the Division:
- Bring down the first coefficient, which is 1.
- Multiply this coefficient by 5 (the value of [tex]\( k \)[/tex]) and write the result underneath the next coefficient.
- Add the result to the next coefficient.

- First Step:
- Bring down the 1:
```
5 | 1 1 -30
|
----------------
1
```
- Multiply: [tex]\( 1 \times 5 = 5 \)[/tex], write under the second coefficient:
```
5 | 1 1 -30
| 5
----------------
1
```
- Add: [tex]\( 1 + 5 = 6 \)[/tex], place under the line:
```
5 | 1 1 -30
| 5
----------------
1 6
```

- Second Step:
- Multiply the last result by 5: [tex]\( 6 \times 5 = 30 \)[/tex], write under the third coefficient:
```
5 | 1 1 -30
| 5 30
----------------
1 6
```
- Add: [tex]\( -30 + 30 = 0 \)[/tex]:
```
5 | 1 1 -30
| 5 30
----------------
1 6 0
```

5. Interpret the Results:
The numbers at the bottom row represent the coefficients of the quotient polynomial and the remainder. Here:

- The quotient polynomial is [tex]\( x + 6 \)[/tex] (represented by 1 and 6).
- The remainder is 0, which means [tex]\( P(5) = 0 \)[/tex].

So, the value of [tex]\( P(k) \)[/tex], where [tex]\( k = 5 \)[/tex], is [tex]\( 0 \)[/tex]. This means [tex]\( 5 \)[/tex] is a root of the polynomial [tex]\( P(x) = x^2 + x - 30 \)[/tex].